1. Field of the Invention
The present invention relates to automatic mechanisms for applying fasteners such as spring clips or the like to work pieces and more particularly to automatic mechanisms for applying spring clips one at a time directly from a storage means such as a bulk loaded hopper onto a properly positioned work piece and for resisting release of spring clips from the hopper escapement in the absence of a work piece properly positioned within an assembly tool nose piece.
2. Description of the Prior Art
Various types of automatic fastener emplacement devices and mechanisms are well known in the prior art. Examples of these prior art devices may be seen by reference to U.S. Pat. Nos. 3,278,105; 3,517,856; 3,543,376; 3,672,029 and 3,702,494.
The prior art mechanisms were less than totally satisfactory as many utilized assembly heads wherein a fastener is held in the head ready for assembly. When the prior art mechanisms were actuated, a ram drove the held fastener out of its holder and on to the work. The fastener applying cycle was then completed as another fastener was released from a hopper mechanism and blown down through a delivery tube and caught and held by a catcher/holder. The catcher/holder devices of the prior art mechanisms tended to wear out or break frequently due to the speed at which the fasteners travel, stop, then are fired on to the work. Many of the prior art devices were also easily actuated to eject a fastener under the full force of a ram in the absence of a work piece properly positioned relative to the nose piece.
The use of stop members and/or catcher/holder devices created a component or group of components subject to excessive wear and/or breakage. Also, fasteners held by the catcher/holder device in a tool head were often not completely visible to the operator and thus were difficult to align with the work piece prior to the assembly therewith and/or were subject to damage and/or jamming of the fastener applying mechanism during the positioning of the work piece relative to the assembly head.
The ability of the prior art mechanisms to easily be caused to eject fasteners, often at a relatively high force supplied by the ram, in the absence of a work piece properly positioned relative to the assembly heads or nose pieces thereof often resulted in the wasteful firing or ejecting of the fasteners, occasionally dangerously at fellow workers and the like. The ability to eject fasteners in the absence of a work piece properly positioned in the nose piece also resulted in improperly applied fasteners and the like.